Dr. John D. Horn High School is a secondary school in Mesquite, Texas, United States.

[2][3] John Horn High School, which serves grades 9 through 12, is a part of the Mesquite Independent School District.

[4] For the 1st time, Horn’s marching band advanced to the UIL State Marching Contest in 2018, in which they placed 22nd, making it the 2nd school in Mesquite to participate in the UIL State Marching competition.

[5] All students at Horn are required to dress according to a standardized dress code (similar to a school uniform).

As of 2005 the code is at all Mesquite ISD middle and high schools.